短文改错 our school lies under the foot of a mountain with a ama

短文改错 our school lies under the foot of a mountain with a amall river paased by.It used to be quite,clean and beautiful place for a school .It is pity which things have changed after a chemical factory was built near your school one year ago.every day the factory produces much waste water and some harmful gases.the terribly pollution is harmful to our health.,what's bad,the great noise from the factory had a bad effect on our activities.